The Chemical Evolution of Milky Way Satellite Galaxies from Keck/DEIMOS Multi-Element Abundance Measurements

A Keck/DEIMOS spectroscopic campaign of eight Milky Way (MW) dwarf spheroidal (dSph) satellite galaxies has generated spectral synthesis-based abundance measurements for nearly 3000 stars. The elements measured are Fe and the elements Mg, Si, Ca, and Ti. The dSph metallicity distributions show that the histories of the less luminous dSphs were marked by massive amounts of gas loss. The [/Fe] distributions indicate that the early star formation histories of most dSphs were very similar and that Type Ia supernova ejecta contributed to the abundances of all but the most metal-poor ([Fe/H] < −2.5) stars.